Die assembly

ABSTRACT

A method and apparatus for forming sheet material, such as light gauge foil, into containers and the like. A punch and die arrangement includes supporting the forming portions of the die assembly by a pressurized fluid such as air so that these portions yieldably conform with precision to the punch surfaces during a forming operation.

United States Patent [72] lnventors Lorenz Tilly [56] References Cited Montreal; UNITED STATES PATENTS gggsf westmmm" Quebec 2,989,0l9 6/1961 Van Sciver 72/351 3,062,262 11/1962 Post 72/336 5; g gg 3,292,415 12/1966 Hoffman 72/351 1 1 e 1 3,372,569 3/1968 Bozek 113/120 [45] Patented May 25, 1971 FOREIGN PATENTS [73] Assignee Universal Alufolien Verfahren A.G.

Z S it l 280,900 5/ 1952 Switzerland 72/351 223,430 10/ 1924 Great Britain 72/349 Primary ExaminerRichard J. Herbst Attorney-Stevens, Davis, Miller and Mosher [54] DIE ASSEMBLY l2 Chums 4 Drawmg Figs ABSTRACT: A method and apparatus for forming sheet [52] U.S. (I 72/336, material, such as light gauge foil, into containers and the like. 2/3 1 3/ l 20 A punch and die arrangement includes supporting the forming [51] Int. Cl B2ld 22/22 portions of the die assembly by a pressurized fluid such as air [50] Field of Search 72/336, so that these portions yieldably conform with precision to the punch surfaces during a forming operation.

Patented May 25, 1971 3 Sheets-Sheet 1 II VE/ TOR S LONE/V2 LL y BHRRIE BOA/IVER HTTORI E/S Patented May 25, 1971 3 Sheets-Sheet 2' Imus/won;

-OKEUZ TILL Patented May 25, 1971 3 She'ets-Sheet 3 m I Mn w Z E R D L R BBQ/us Bowl Ex DIE ASSEMBLY This invention relates to a punch and die assembly arranged for the forming and production of light metal objects and in particular to the formation of rigid foil containers, such as pie plates, frozen food containers and the like.

Known die assemblies utilize a punch and die assembly mounted on a reciprocating punch press with the punch assembly mounted on the vertically reciprocating ram of the press and the die assembly mounted on the bed of the press. Metal foil or the like is fed between the punch and die assemblies and as the punch reciprocates toward and away from the die assembly the foil is punched out and formed into the required container configuration.

Several disadvantages have always been attendant upon such known systems. The die assemblies include one or more draw rings for forming the sidewalls and flanges of the foil containers and these draw rings have been mounted about the center die block by means of pressure pins passing through the press bolster plates. It has been necessary when changing one die for another to remove and drill the press bolster plate to suit each die, this having to be repeated if the dies are to be used on more than one particular punch press. Furthermore, it has been very diffic'ult to obtain an even pressure on the foil during the forming operation. Air cylinders have been externally connected to the punch press and they have been connected to the die draw rings via the pressure pins. Additionally, the pressure pin system which is at present widely used in the industry requires extremely critical and lengthy or changeover time. Because the pressure exerted by the cylindens has been localized to within the immediate area of each pressure pin, any misalignment of the air cylinder has resulted in uneven pressure on the die draw rings with the result being an uneven and consequently a weakened end product. It will be appreciated that if a given operation is using foil of three thousandths of an inch thickness and there is a one thousandths error in the alignment of the punch and die assemblies, this consists of a 30 percent error in misalignment and the end product will exhibit noticeable tears especially in foil containers which have to be formed in a deep draw process. Further, with the die assembly in a misaligned state, the foil containers will exhibit an uneven fold pattern in their sidewalls.

The present invention provides a much simplified apparatus over the known devices, a vastly improved method of operation and a noticable upgrading of the product obtained by this method and apparatus. This invention eliminates the abovementioned difiiculties by effectively integrating the air pressure system into the body of the die assembly in a simple and trouble free manner and at the same time eliminating the mechanical pin connection system. A further result emanating from this invention is that the type of die in accordance with this disclosure can be set up on any punch press without any modification to the bolster plate thereof. The press shutdown time is drastically reduced and the dies can be quickly interchanged for the production of containers of various configuration. The setup or changeover operation is changed from a highly skilled to a relatively unskilled operation.

According to the present invention, an apparatus for forming sheet material, such as foil, comprises a punch and die assembly which is adapted to receive the sheet material therebetween. One of the assemblies is movable toward and away from the other assembly to effect the repetitive punching and fomling operations on the material. At least one peripheral ring member on one of the assemblies is movable with respect to that assembly between an idle, inoperative position when the foil is placed in the apparatus and in which the ring member assists in supporting the sheet material between the punching operations and an operative position for forming the sheet material into the required configuration. A pressurized fluid such as air is utilized to yieldably support one of the assemblies so that the ring member is in effect free floating and will be self levelling and aligning with respect to the other assembly. This pressure is directed onto the draw ring without the intervention of the known pressure pins and is therefore absolutely evenly distributed at all times.

The invention will be described by way of example with reference to the accompanying drawings in which FIG; 1 is a perspective view of the well-known foil containe of the pie plate type;

FIG. 2 is a cross-sectional view of the punch and die assembly for manufacturing the container shown in FIG. 1, the left side of FIG. 2 showing the assembly in the open or inoperative position and the right-hand side of FIG. 2 showing the apparatus in the operative or forming position;

FlG. 3 shows another type of container of greater depth than that shown in FIG. 1 and which is manufactured by the deep draw process; and

FIG. 4 is a cross-sectional view of a punch and die assembly for deep drawing metal foil to provide the product shown in FIG. 3, the left-hand side of FIG. 4 showing the punch and die assembly in the open or inoperative position adapted to receive the foil and the right-hand side showing the punch and die assembly in the operative or forming position.

Referring to FIG. 1, a container 1 is formed in the configuration of a pie plate and includes a bottom wall 2, a sidewall 3 terminating at the upper end thereof in a flat flange 4 and a curled ring 5 at the extreme outer edge. The sidewall 3 of the container displays flutes or creases 6 of substantial uniformity.

Turning now to FIG. 2, the apparatus for forming the metal container shown in FIG. 1 comprises a punch assembly shown generally at 10 and a die assembly shown generally at 12. Both the punch assembly 10 and the die assembly 12 may be mounted on a suitable actuating means such as a punch press, not shown.

The punch assembly 10 includes a base 14 which may be secured to the ram of a punch press, an outer (in this illustration, upper) punch ring 16 secured to the base and acenter form 18 which is provided with a cavity 20, the configuration of which conforms to the bottom wall 2 and sidewall 3 of the container shown in FIG. 1. Center form 18 is provided with a circumferential groove 22 on its outer wall and a suitable gasket such as a sealing ring 24 is placed within this groove to provide air-sealing engagement between the outer wall of center form 18 and the inner peripheral wall of the upper punch ring 16. A suitable amount of pressurized air or other fluid is injected into a space 26 between the center form and the base 14 by way of an air line 29. This air can be fed, for example, from a surge tank or the like, now shown. The pressure in the space 26 maintains the center form 18 of the punch assembly in the position (inoperative) shown in the left-hand side of FIG. 2 in which a shoulder 28 on the center form engages a juxtaposed shoulder 30 on the punch ring 16. It'will be appreciated from the right-hand side of FIG. 2 that when the punch assembly is brought down into the operative or forming position, the center form 18 yields under the punching process to compress the air in the space 26 and absorb any shock in the formation stroke.

The die assembly 12 is mounted, by way of example, on a press bolster plate 32 by.means of a suitable connection 34 between the bolster plate 32 and the die center block 36. .The center block 36 is adapted to mate with the cavity 20 in the punch center form 18 to assist in the formation of the bottom wall 2 and the sidewall 3 of the container as shown in FIG. 1. A cut-edge ring 38 is also secured to the press bolster plate 32 and the ring 38 is concentric with the die block 36 but its diameter is such that a circumferential space or cavity 40 is provided between the die center block 36 and the cut-edge ring 38.

The cavity 40 serves to accommodate at least one draw ring, or more, depending on the type of flange used on anygiven container manufactured in this apparatus. In the embodiment shown in FIG. 2, two rings are situated in the cavity 40, an outer draw ring 42 and an inner draw ring 44. Shoulders46 provide a limit to the upward movement of the rings 42 and 44 towards their inoperative position shown in the left-hand side of FIG. 2. Additionally, shoulders 48 on the center block 36 and the inner draw ring 44 serves additionally to provide upward limited movement between the ring 44 and the die block 36.

In the operative or forming position, the inner and outer draw rings 42and 44 assume the position shown on the righthand side of FIG. 2 and it will be noted that the base 50 of the draw ring 44 comes to rest at position 52 on the press bolster plate 32.

Suitable gaskets are provided on the outer draw ring 42 and the die center block 36 to provide a substantially airtight cavity 40. Center block 36 has a circumferential groove 54 machined therein toaccommodate a seal ring 56. This seal ring, it will be noted, provides sealing engagement between the die block 36 and the inner draw ring 44. Additionally, draw ring 42 is provided with an inner groove 58 and an outer groove 60 so as to accommodateinner and outer seal rings 62 and 64, respectively. It will be appreciated that seal ring 62 provides sealing engagement between inner and outer draw rings 42 and 44 and the outer seal ring 64 provides similar engagement between the outer wall of the outer draw ring 42 and the inner wall of the cut-edge ring 38.

Air pressure is injected into the cavity 40 by means of a conduit 66 and 68.

It will be understood that the absence of pressure pins and similar mechanical connections between the draw rings 42 and 44 and the press bolster plate 32 will allow a substantial amount of self-alignment to be made by these rings during the forming operation. Moreover, the provision of the gaskets on these draw ringsas well as on the die center block 36 dictates the allowance of sufficient clearance being provided between the cut-edge ring 38, inner and outer draw rings 42 and 44 and die block center 36, to allow such self-alignment. In addition, a sufficient clearance may be provided between the center form 18 of the punch assembly and the inner walls of the upper punch ring 16 to allow similar self-alignment of the center form 18.

When the ram of the punch press reciprocates the punch assembly towards the forming position with the die assembly 12, the press center form 18 presses the metal foil between the form 18 and the corresponding surface of the die center block 36. Additionally, a flange 70 on the press center form 18 engages the foil material 15 and impresses the same against the upper surface of the inner draw ring 44 to form the flange 4 of the container shown in FIG. 1. In this operation, the inner draw ring 44 yields downwardly to conform with the surface and alignment of the flange 70 of the center form of the press 18 to the position shown in the right-hand side of FIG. 2. Additionally, the outer draw ring 42 yields in conformity to the surface of the upper punch ring 16 of the press assembly 10 so that the outer draw ring 42 assumes the position in the cavity 40 as shown on the right-hand side of FIG. 2. Here again, the ring 42 may conform to any misalignment in the punch ring 16 due to its peripheral clearance and gasket provisions. It will also be noted that the press center form 18 also yields under the punching operation to a compressing position with respect to the space 26.

As the ram of the punch press retracts, the pressure on the lower surfaces of the inner and outer draw rings 44 and 42 cause them to be pressed upwardly to their inoperative position shown on the left-hand side of FIG. 2 and at the same time the extreme outer edges of the foil container are formed with the curl 5 through the upward movement of the outer draw ring 42 and in particular by the upward wiping action of the curling groove 72. As the rings 42 and 44 reach their uppermost position, they eject the plate 1 from the formed position and it may be removed from the punch press, for example, by air ejection.

Turning now to FIG. 3, a rectangular-shaped container 7 has a bottom wall 8, a sidewall structure 9, a rim flange 11 terminating in a curled outer edge 13. It will be noted that the sidewall 9 of container 7 is substantially deeper than the corresponding wall 3 of container 1 shown in FIG. 1 and container 7 is a deep drawn container by virtue of this depth. Normally, deep drawing requires the use of a heavier gauge foil to avoid the tearing thereof in the forming operation. It will be appreciated from FIG. 4 and from FIG. 3 that if the punch and die assemblies are not precisely aligned it would be easy to have a portion of the sidewall of the container torn during the long folding stroke between the bottom wall of the container and the flange thereof. However, in addition to the excessive cost of having a heavy gauge material, it also is prone to excessive and heavy wrinkling as well as stretching at the points of highest stress. The apparatus of FIG. 4 overcomes the problems of the prior art by successfully manufacturing deep drawn containers from thin metal foil, such as that used in shallow drawn containers, and includes the inventive structure and function of the FIG. 2 embodiment.

The embodiment disclosed in FIG. 4 is similar to that in the F IG. 2 embodiment inasmuch as it includes a punch assembly 74 adapted to be secured, for example, to the ram of a punch press and a die assembly 76 which is adapted for securement to the bolster plate 78 of the punch press. The left-hand portion of FIG. 4 shows the punch and die assemblies 74 and 76 in an open or inoperative position and in readiness to receive a sheet of foil material 17 for forming thereof. The right-hand side of FIG. 4 shows the assemblies in a forming or operative position. The punch assembly includes a punch ring 78 and a center form 80, the latter having a cavity 82 providing the required configuration to form the sidewall 9 and bottom wall 8 of the container shown in FIG. 3. The center form is resiliently mounted in the punch assembly 74 by a seal ring 84 similar to that of FIG. 2. Additionally, the center form 80 includes a peripheral shoulder 86 adapted to engage a corresponding shoulder 88 on the upper punch ring 78 when the apparatus is in the inoperative position, these shoulders providing a means to limit the downward movement of the center form 80 in the punch assembly. This movement is provided by air pressure fed into at least one chamber 90 through a supply line 92. It will be appreciated from a view of the righthand side of FIG. 4 and especially the spacing between the shoulders 86 and 88, that there is a substantial shock absorb-. ing action in the punch assembly during the forming stroke.

The die assembly 76 includes a center block 94 which is suitably secured to the press bolster plate 78. A cut-edge ring 96 is mounted on the press bolster plate 78 by spacers 98, this mounting being concentric with the die center block 94, but spaced radially therefrom to provide a peripheral cavity 100 around the die block 94.

A draw ring 102 is positioned in the cavity 100 for vertical movement therein between the lower operative position in which the draw ring 102 assists in forming the flange 11 and curled edge 13 of the container shown in FIG. 3; and the upper or inoperative position for supporting the foil 17 prior to the punching operation. Draw ring 102 is provided with a peripheral shoulder 104 which is adapted to engage a mating shoulder 106 on the lower inner edge of the cut-edge ring 96 when the draw ring 102 is in its inoperative position.

The cavity 100, as it appears on the left-hand side of FIG. 4, comprises a quite substantial cubic area. Considering the acceleration of the downstroke of the punch press, there could be an air disposal problem if the draw ring 102 were to be supported in a similar manner to that in FIG. 2, i.e. a complete air cushion around the periphery of the die block. It will be appreciated that if the air disposal is too great, this may result in serious tearing of the thin sheet material on a deep draw process.

To solve this problem of air disposal on deep draw processes, the present embodiment provides supporting telescopic columns or cylinders 108 which are slidably secured at their lower ends to the press bolster plate 78 and at their upper ends to the draw ring 102. In general, only ambient atmospheric pressure exists in the cavity 100 around the die center block 94 and pressurized fluid such as air is received only within the confines of the columns 108, this air being injected through lines 110. As mentioned with respect to the previous embodiment, a surge tank may be connected to the lines 110 to absorb the exhaust of air from the telescopic columns 108.

As shown in the left-hand side of FIG. 4, the columns 108 comprise a plurality of tubes 112 (in this case four). Tubes 112 are slidable within one another and are rendered airtight by means of circumferential grooves 114 accommodating seal rings 116 on each tube and which are adapted to slidably and sealingly engage the walls of the next larger tube. At the lower end of the column 108, the lowermost tube 112d is slidably mounted in one of a plurality of subcavities 118. A collar member 120 is positioned around the upper rim of the subcavity 118 and the collar 120 includes an annular groove and seal ring 122 for sealingly engaging the outer surface of the lowermost tube1l2d.

The number of telescopic columns 108 will depend on the overall size of the container to be manufactured by this deep drawn process; a relatively small container might require only four such columns distributed evenly around the cavity 100. In one example, a container such as that shown in FIG. 3 has been manufactured and its measurements are in the region of 9% inches sluare with a depth of 2% inches. On the apparatus for manufacturing this container, eight tubes 108 have been placed in the die assembly and have been disposed in such a manner that there are two columns adjacent each sidewall area of the die ,center block 94. Moreover, the number of tubes in each column and the diameter thereof will depend on the depth of the container, the width of the flange, etc.

In the forming position shown in the right-hand side of FIG. 4, the punch assembly has formed the foil into the shape of the container with the terminal edge 124 of the punch center form engaging a peripheral shoulder 126 on thedie center block 94. The outer periphery of the foil, as it is punched out, is drawn down past the die block 94 and shoulder 126 by the operative face of the upper punch ring 78 and the juxtaposed gripping surface of the draw ring 102. It will be seen that in this opera tive position at the lower end of the stroke of the punch press, the tubes 112 of the columns 108 are telescoped downwardly into a stored position in the subcavity 118. When the punch assembly is retracted by the ram or other actuating means to which it is attached, the fluid pressure entering the interior of the telescopic columns effects raising of the draw ring 102 to its inoperative position and in so doing a curl groove 128 on the draw ringefiects turning of the terminal peripheral edge of the container 7 to provide the curl 13 shown in FIG. 3. Subsequent to this curl being formed and the draw ring 102 being raised completely to its inoperative position, the container is ejected from the die block 94 and may be removed from the area of the punch press, such as by air rejection.

It is to be understood that in both embodiments of this invention, surge tanks may be used both for the upper and lower fluid supplies. The degree of pressure used in the formation of a foil container varies in accordance with the size of the container and the thickness of the material being formed. By way of example, the FIG. 2 embodiment in manufacturing say, an 8 inch plate could operate with a pressure of 60 to 80 pounds in the space designated as 26 in FIG. 2 and with a pressure of probably 40 pounds in the cavity between the inner and outer draw rings 42 and 44 in the die assembly, the fluid in this core being air. Other gaseous or hydraulic fluids may of course be suitable. The invention need not be limited to use in a punch press, but can be utilized in any reciprocating forming machine where a sufficient surface pressure may be applied to fonn articles.

It is important to note that die changeover time, as now practiced in the art, may take up to 4 or even 8 hours of a skilled workman's time. With the assemblies according to the present invention, this time is reduced to a matter of minutes. Additionally, various types of gasket or sealing rings may be used on the components of the embodiments of this invention, such as O-rings, quad rings, etc. so long as the desired sealing engagement is provided.

The support of die draw rings by fluid pressure such as air and the result of the forming surfacesyieldably conforming to the opposite surfaces in the punch mechanism provides a foil container displaying an accuracy of dimension and quality, both of which have been previously unknown in this art.

We claim:

1. In the process of forming sheet material in which a punch assembly and die assembly receive the sheet material therebetween and the punch assembly is reciprocated toward and away from the die assembly to effect repetitive punching and forming operations on the material and wherein at least one peripheral ring member is provided on the die assembly and is movable with respect thereto between an inoperative position for supporting the sheet material between punching operations and an operative position for forming the sheet material into shape; an improved method of the forming process which comprises providing a pressurized gaseous fluid to directly and resiliently support said ring member on the die whereby the ring is free-floating and self-levelling with respect to the punch assembly and will yieldably conform to the surfaces of the punch assembly during a forming operation.

2. In the process of forming sheet material in which a punch assembly and die assembly receive the sheet material therebetween, and one of said assemblies is reciprocated toward and away from the other assembly to effect repetitive punching and forming operations on the material; and in which peripheral ring members are movably mounted on the die assembly between an inoperative position for supporting the sheet material between punching operations and an operative position for forming the sheet material into shape; an improved method of the forming process which consists of injecting a pressurized gaseous fluid in the die assembly and punch assembly to resiliently support said assemblies with respect to one another; and free-floating said ring members on the die assembly by direct support of the gaseous fluid so that the ring members yieldably conform with precision to the surfaces of the punch assembly during a forming operation.

3. Apparatus for forming sheet material comprising a punch assembly and die assembly adapted to receive the sheet material therebetween, said punch assembly being reciprocally movable'toward and away from the die assembly to effect repetitive punching and forming operations on the material; at least one peripheral ring member on the die assembly, said ring being movable with respect thereto between an inoperative position for supporting the sheet material between punching operations and an operative position for forming the sheet material into shape; and a pressurized gaseous fluid directly and yieldably supporting said ring member on the die assembly whereby the ring is free'floating and self-levelling with respect to the punch assembly.

4. Apparatus according to claim 3 including a plurality of telescopic columns disposed about the die assembly and supporting said ring member; the pressurized gaseous fluid being restricted to the interior of said columns.

5. Apparatus for forming sheet material'comprising a punch assembly and die assembly adapted to receive the sheet material therebetween,, said punch assembly beingreciprocally movable toward and away from'the die assembly to effect repetitive punching and forming operations on the material at least one peripheral ring member mounted circumferentially on the die assembly and being movable withrespect to the die between an inoperative position for supporting the sheet material between punching operations and an operative position for forming the sheet material into shape; and a pressurized gaseous fluid resiliently and directly supporting the ring member to its inoperative position with respect to the die whereby the ring is free-floating and self-levelling with respect to the punch assembly and yieldable with respect thereto during forming of the sheet material.

6. Apparatus according to claim 5 wherein said pressurized gaseous fluid is air.

7. Apparatus according to claim 5 including a'cavity in the die assembly to accommodate said ring in'its operative position; and a plurality of'telescopic columns positioned in the cavity and being secured to and supporting said ring member,

said columns receiving the pressurized gaseous fluid to move said ring to its inoperative position.

8. Apparatus for forming metal foil containers on a punch press having a bed and reciprocating ram, said apparatus comprising a punch assembly on the ram and a die assembly on the bed; the punch assembly including a punch ring secured to said ram and a center form, having a cavity, positioned for limited vertical movement in the punch ring; the die assembly including a center block secured to said bed and having an upper surface corresponding to the cavity in the punch center form to effect shaping therebetween of a foil container; a cut edge ring on said bed concentric with but spaced radially from the center block; an inner draw ring and an outer draw ring 1 positioned for limited vertical movement in the space between the cut edge ring and the center block; said draw rings having an upper, inoperative position for supporting said metal foil and a lower operative position when engaged by the punch curl ring and center form; a peripheral cavity beneath said draw rings; gasket means on the components of the die assembly to provide a substantially airtight relationship between the cut edge ring, draw rings and center block; said cavity being adapted to receive pressurized air therein to directly support said draw rings thereby to (a) allow the draw rings to yieldably conform with precision to the forming faces of the punch assembly during a fonning operation and (b) to effect movement thereafter of the rings to the inoperative position and to ejectthe fon'ned container from the die assembly.

9. Apparatus according to claim 8 including circumferential grooves on the die center block and the outer draw ring and wherein the gasket means comprises seal rings in said grooves to provide air sealing engagement between the cut edge ring, the draw rings and the die center block.

10. Apparatus for forming metal foil containers on a punch press having a bed and reciprocating ram, said apparatus comprising a punch assembly on the ram and a die assembly on the bed; the punch assembly including a punch ring secured to said ram and a punch center form having a cavity and positioned for limited vertical movement in the punch ring; the die assembly including a center block secured to said bed and having a surface corresponding to the cavity in the punch center form to effect shaping therebetween of a foil container; a cut edge ring on said bed concentric with but spaced radially from the center block; a draw ring positioned for limited vertical movement in the space between the cut edge ring and the center block; said draw ring having an upper, inoperative position for supporting said metal foil and a lower operative position when engaged by the punch ring; a peripheral cavity beneath said draw ring; and a plurality of substantially fluidtight telescoping columns secured at their lower ends in said cavity and at their upper ends to said draw ring; the columns being adapted to receive pressurized air therein to (a) allow the draw ring to yieldably conform with precision to the opposed surfaces of the punch assembly during a forming operation and (b) to effect movement thereafter of the ring to its inoperative position and to eject the formed container from the die assembly.

11. Apparatus according to claim 10 wherein the telescopic columns consist of interfitting tubes of gradually reduced diameter, the outer periphery of each tube slidably engaging the inner periphery of the adjacent larger tube; grooves in the outer periphery of the tubes and seal rings in said grooves for rendering the columns airtight.

12. Apparatus for forming metal foil containers comprising a punch assembly and die assembly adapted to receive the metal foil therebetween, said punch assembly being reciprocally movable toward and away from the die assembly to effect repetitive punching and forming operations on the foil; at least one peripheral ring member mounted circumferentially on the die assembly and being movable with respect to the die between an inoperative position for supporting the foil between punching operations and an operative position for forming the foil into shape; a peripheral cavity beneath said rin pressurized air in'ected into said cavity for directly and res iently supporting t e ring member to its inoperative position on the die whereby the ring is free-floating and selflevelling on the pressurized air with respect to the punch assembly so that it will yieldably conform to said punch assembly during forming of the metal foil containers; and seal rings on said ring member to provide a substantially airtight relationship between said ring member and the die assembly. 

1. In the process of forming sheet material in which a punch assembly and die assembly receive the sheet material therebetween and the punch assembly is reciprocated toward and away from the die assembly to effect repetitive punching and forming operations on the material and wherein at least one peripheral ring member is provided on the die assembly and is movable with respect thereto between an inoperative position for supporting the sheet material between punching operations and an operative position for forming the sheet material into shape; an improved method of the forming process which comprises providing a pressurized gaseous fluid to directly and resiliently support said ring member on the die whereby the ring is free-floating and selflevelling with respect to the punch assembly and will yieldably conform to the surfaces of the punch assembly during a forming operation.
 2. In the process of forming sheet material in which a punch assembly and die assembly receive the sheet material therebetween, and one of said assemblies is reciprocated toward and away from the other assembly to effect repetitive punching and forming operations on the material; and in which peripheral ring members are movably mounted on the die assembly between an inoperative position for supporting the sheet material between punching operations and an operative position for forming the sheet material into shape; an improved method of the forming process which consists of injecting a pressurized gaseous fluid in The die assembly and punch assembly to resiliently support said assemblies with respect to one another; and free-floating said ring members on the die assembly by direct support of the gaseous fluid so that the ring members yieldably conform with precision to the surfaces of the punch assembly during a forming operation.
 3. Apparatus for forming sheet material comprising a punch assembly and die assembly adapted to receive the sheet material therebetween, said punch assembly being reciprocally movable toward and away from the die assembly to effect repetitive punching and forming operations on the material; at least one peripheral ring member on the die assembly, said ring being movable with respect thereto between an inoperative position for supporting the sheet material between punching operations and an operative position for forming the sheet material into shape; and a pressurized gaseous fluid directly and yieldably supporting said ring member on the die assembly whereby the ring is free-floating and self-levelling with respect to the punch assembly.
 4. Apparatus according to claim 3 including a plurality of telescopic columns disposed about the die assembly and supporting said ring member; the pressurized gaseous fluid being restricted to the interior of said columns.
 5. Apparatus for forming sheet material comprising a punch assembly and die assembly adapted to receive the sheet material therebetween, said punch assembly being reciprocally movable toward and away from the die assembly to effect repetitive punching and forming operations on the material at least one peripheral ring member mounted circumferentially on the die assembly and being movable with respect to the die between an inoperative position for supporting the sheet material between punching operations and an operative position for forming the sheet material into shape; and a pressurized gaseous fluid resiliently and directly supporting the ring member to its inoperative position with respect to the die whereby the ring is free-floating and self-levelling with respect to the punch assembly and yieldable with respect thereto during forming of the sheet material.
 6. Apparatus according to claim 5 wherein said pressurized gaseous fluid is air.
 7. Apparatus according to claim 5 including a cavity in the die assembly to accommodate said ring in its operative position; and a plurality of telescopic columns positioned in the cavity and being secured to and supporting said ring member, said columns receiving the pressurized gaseous fluid to move said ring to its inoperative position.
 8. Apparatus for forming metal foil containers on a punch press having a bed and reciprocating ram, said apparatus comprising a punch assembly on the ram and a die assembly on the bed; the punch assembly including a punch ring secured to said ram and a center form, having a cavity, positioned for limited vertical movement in the punch ring; the die assembly including a center block secured to said bed and having an upper surface corresponding to the cavity in the punch center form to effect shaping therebetween of a foil container; a cut edge ring on said bed concentric with but spaced radially from the center block; an inner draw ring and an outer draw ring positioned for limited vertical movement in the space between the cut edge ring and the center block; said draw rings having an upper, inoperative position for supporting said metal foil and a lower operative position when engaged by the punch curl ring and center form; a peripheral cavity beneath said draw rings; gasket means on the components of the die assembly to provide a substantially airtight relationship between the cut edge ring, draw rings and center block; said cavity being adapted to receive pressurized air therein to directly support said draw rings thereby to (a) allow the draw rings to yieldably conform with precision to the forming faces of the punch assembly during a forming operation and (b) to effect movement thereafter of the rings to the inOperative position and to eject the formed container from the die assembly.
 9. Apparatus according to claim 8 including circumferential grooves on the die center block and the outer draw ring and wherein the gasket means comprises seal rings in said grooves to provide air sealing engagement between the cut edge ring, the draw rings and the die center block.
 10. Apparatus for forming metal foil containers on a punch press having a bed and reciprocating ram, said apparatus comprising a punch assembly on the ram and a die assembly on the bed; the punch assembly including a punch ring secured to said ram and a punch center form having a cavity and positioned for limited vertical movement in the punch ring; the die assembly including a center block secured to said bed and having a surface corresponding to the cavity in the punch center form to effect shaping therebetween of a foil container; a cut edge ring on said bed concentric with but spaced radially from the center block; a draw ring positioned for limited vertical movement in the space between the cut edge ring and the center block; said draw ring having an upper, inoperative position for supporting said metal foil and a lower operative position when engaged by the punch ring; a peripheral cavity beneath said draw ring; and a plurality of substantially fluidtight telescoping columns secured at their lower ends in said cavity and at their upper ends to said draw ring; the columns being adapted to receive pressurized air therein to (a) allow the draw ring to yieldably conform with precision to the opposed surfaces of the punch assembly during a forming operation and (b) to effect movement thereafter of the ring to its inoperative position and to eject the formed container from the die assembly.
 11. Apparatus according to claim 10 wherein the telescopic columns consist of interfitting tubes of gradually reduced diameter, the outer periphery of each tube slidably engaging the inner periphery of the adjacent larger tube; grooves in the outer periphery of the tubes and seal rings in said grooves for rendering the columns airtight.
 12. Apparatus for forming metal foil containers comprising a punch assembly and die assembly adapted to receive the metal foil therebetween, said punch assembly being reciprocally movable toward and away from the die assembly to effect repetitive punching and forming operations on the foil; at least one peripheral ring member mounted circumferentially on the die assembly and being movable with respect to the die between an inoperative position for supporting the foil between punching operations and an operative position for forming the foil into shape; a peripheral cavity beneath said ring; pressurized air injected into said cavity for directly and resiliently supporting the ring member to its inoperative position on the die whereby the ring is free-floating and self-levelling on the pressurized air with respect to the punch assembly so that it will yieldably conform to said punch assembly during forming of the metal foil containers; and seal rings on said ring member to provide a substantially airtight relationship between said ring member and the die assembly. 